Dip-coating Technique Research Articles

Low-temperature electrical transport and tunable optical properties of Mo-doped V2O3 thin films

This work reports the structural and low-temperature electrical transport properties of Mo doped V2O3 single-layer thin films (i.e., with compositions between Mo and V2O3 [V2−xMoxO3−δ (x = 0, 0.05–0.1)]) deposited on alumina (Al2O3) substrates by sol–gel dip-coating technique. The crystallinity of the V2O3 films is modified with the high concentration of Mo doping and exhibits a relatively defective structure compared to that of pure V2O3 films. The low temperature (i.e., over a temperature range of 253.15 to 273.15 K) electrical hysteresis curves reveal that the triggering of metal–insulator transition at low temperatures. The metal–insulator transition (MIT) temperature (Tc) values are found to be 258.49 and 261.11 K for 8 and 10 mol% Mo doped V2O3 films, respectively, which are higher than that of undoped V2O3 (Tc = 253.09 K). The experimental results contribute a promising method to develop a novel material for high-performance low-temperature engineering applications.

A Review of Electro Conductive Textiles Utilizing the Dip-Coating Technique: Their Functionality, Durability and Sustainability.

The presented review summarizes recent studies in the field of electro conductive textiles as an essential part of lightweight and flexible textile-based electronics (so called e-textiles), with the main focus on a relatively simple and low-cost dip-coating technique that can easily be integrated into an existing textile finishing plant. Herein, numerous electro conductive compounds are discussed, including intrinsically conductive polymers, carbon-based materials, metal, and metal-based nanomaterials, as well as their combinations, with their advantages and drawbacks in contributing to the sectors of healthcare, military, security, fitness, entertainment, environmental, and fashion, for applications such as energy harvesting, energy storage, real-time health and human motion monitoring, personal thermal management, Electromagnetic Interference (EMI) shielding, wireless communication, light emitting, tracking, etc. The greatest challenge is related to the wash and wear durability of the conductive compounds and their unreduced performance during the textiles' lifetimes, which includes the action of water, high temperature, detergents, mechanical forces, repeated bending, rubbing, sweat, etc. Besides electrical conductivity, the applied compounds also influence the physical-mechanical, optical, morphological, and comfort properties of textiles, depending on the type and concentration of the compound, the number of applied layers, the process parameters, as well as additional protective coatings. Finally, the sustainability and end-of-life of e-textiles are critically discussed in terms of the circular economy and eco-design, since these aspects are mainly neglected, although e-textile' waste could become a huge problem in the future when their mass production starts.

Corrosion inhibition performance of polyolefin smart self-healing composite coatings modified with ZnO@β-Cyclodextrin hybrid particles

Corrosion is a global problem that results in substantial economic loss and is life-threatening as well. Currently, the utilization of self-healing coatings involving smart carriers encapsulated with the appropriate self-healing agents is a topic of great interest. Following this strategy, our work reports the synergistic corrosion inhibition performance of polyolefin-based smart coatings containing modified hybrid-based particles. The hybrid particles (ZnO@β-CD) comprising zinc oxide (ZnO) and β-Cyclodextrin (β-CD) were synthesized and modified with 2-mercaptobenzothiazole (2-MBT). The synthesized unmodified and modified hybrid particles were characterized by numerous techniques. TGA analysis confirmed that 2MBT was effectively loaded into ZnO@β-CD with almost 43% loading. UV-vis spectroscopic analysis results suggested that the self-release behavior of 2MBT is more pronounced in the acidic environment compared to the basic and neutral environment due to the dissociation of ZnO in the acidic environment. In the next stage, the synthesized unmodified (ZnO@β-CD) and modified (ZnO@β-CD-2MBT) hybrid particles were reinforced into a polyolefin matrix, followed by its application on steel substrate via dip-coating technique to formulate smart composite coatings. The Electrochemical impedance spectroscopy (EIS) results conducted on the developed smart composite coatings demonstrated that polyolefin coatings reinforced with modified hybrid particles (ZnO@β-CD-2MBT) displayed improved corrosion inhibition performance (98 GΩ cm2) as compared to the composite coatings (87 GΩ cm2) containing unmodified particles ((ZnO@β-CD) in 0.56 M NaCl solution after 20 days of immersion. This decent improvement in corrosion resistance behavior is attributed to the synergistic corrosion inhibition effect experienced due to the combined corrosion inhibition effect of ZnO and 2MBT.

Sol-Gel Derived Silica-Titania Waveguide Films for Applications in Evanescent Wave Sensors-Comprehensive Study.

Composite silica-titania waveguide films of refractive index ca. 1.8 are fabricated on glass substrates using a sol-gel method and dip-coating technique. Tetraethyl orthosilicate and tetraethyl orthotitanate with molar ratio 1:1 are precursors. Fabricated waveguides are annealed at 500 °C for 60 min. Their optical properties are studied using ellipsometry and UV-Vis spectrophotometry. Optical losses are determined using the streak method. The material structure and chemical composition, of the silica-titania films are analyzed using transmission electron microscopy (TEM) and electron dispersive spectroscopy (EDS), respectively. The surface morphology was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) methods. The results presented in this work show that the waveguide films are amorphous, and their parameters are stable for over a 13 years. The optical losses depend on their thickness and light polarization. Their lowest values are less than 0.06 dB cm-1. The paper presents the results of theoretical analysis of scattering losses on nanocrystals and pores in the bulk and interfaces of the waveguide film. These results combined with experimental data clearly indicate that light scattering at the interface to a glass substrate is the main source of optical losses. Presented waveguide films are suitable for application in evanescent wave sensors.

In Situ Growth of Nanosilver on Fabric for Flexible Stretchable Electrodes.

Flexible sensing can disruptively change the physical form of traditional electronic devices to achieve flexibility in information acquisition, processing, transmission, display, and even energy, and it is a core technology for a new generation of the industrial internet. Fabric is naturally flexible and stretchable, and its knitted ability makes it flexibility and stretchability even more adjustable. However, fabric needs to be electrically conductive to be used for flexible sensing, which allows it to carry a variety of circuits. The dip-coating technique is a common method for preparing conductive fabrics, which are made conductive by attaching conductive fillers to the fabrics. However, the adhesion of the conductive fillers on the surface of such conductive fabrics is weak, and the conductive property will decay rapidly because the conductive filler falls off after repeated stretching, limiting the lifespan of flexible electronic devices based on conductive fabric. We chose multifunctional nanosilver as a conductive filler, and we increased the adhesion of nanosilver to fabric fiber by making nanosilver grow in situ and cover the fiber, so as to obtain conductive fabric with good conductivity. This conductive fabric has a minimum square resistance of 9 Ω/sq and has better electrical conductivity and more stable electrical properties than the conductive fabric prepared using the dip-coating process, and its square resistance did not increase significantlyafter 60 stretches.

Thermal neutrons effect on improvement of electrical properties at CIGS thin film derived by sol-gel dip coating technique

The thermal neutron effect on the copper indium gallium (di)selenide thin film synthesized by the sol-gel dip-coating technique has explained the novel use of this film under extreme conditions (such as neutron irradiation fields). The thin film samples were treated by using the reactor neutrons to obtain the optimum neutron treatment for the determination of the variations in the structural characteristics. The gamma filter system has provided the evaluation of the high thermal neutron flux effect on the thin film samples by using the tangential beam tube of ITU TRIGA Mark–II reactor. The influence of the neutron effect on the electrical and optical features was explained by the rise of selenium amount in the thin film. The neutron-treated thin film samples (at 50 at. % Se) had a significant effect on the lowest electrical resistivity depending on the increase of the film density. The equivalent gamma dose of the neutron-treated thin film was determined as a 0.024 Gy dose level for neutron irradiation. The neutron treatment was significant to evaluate the decrease in the sheet resistivity of the thin film at this dose level. The neutron dose has led to a slight decrease in the optical band gap as the result of the thermal and epithermal neutrons' effects on the thin film.

Degradation of oily effluents using immobilized photocatalyst: Laboratory experimentation and plant design

In the present work, a simple and flexible solar detoxification system is proposed for the removal of oil contaminants from oily wastewaters. The proposed system can be installed on oil production platforms or on the nearest coastline. Experiments on photocatalytic degradation of oily wastewater were conducted using an immobilized TiO2 catalyst on Pyrex glass tubes (fixed in the focal line of the compound parabolic collector (CPC) using the dip-coating technique). Solar irradiation was the main energy source, while UV irradiation was tested for comparison purposes. The effects of volume flow, initial oil concentration, and addition of hydrogen peroxide on oil degradation were tested. Using an artificial UV lamp and an initial oil concentration of 120 ppm, an oil degradation percentage of 75 % was achieved at a flow rate of 18 ml/s. The results of the effect of initial oil concentration showed oil degradation of 53, 65, 77 and 79 % for initial concentrations of 120, 80, 60 and 40 ppm, respectively. The addition of 0.9 M H2O2 and 1 M H2O2 improved hydrocarbon degradation and resulted in degradation levels of 87 % and 100 %, respectively. The design characteristics of the plant are described based on a capacity of 100 tons of oil spill.

Enhancing selectivity of solar absorber using reduced graphene oxide modified nickel oxide nanocomposite thin films

Commercial solar selective absorbers prepared through several techniques have encountered drawbacks of necessitating complicated and expensive equipment, substantial materials requirement, and polluting environment. In this context, carbon incorporated metal oxide thin films have shown promise of low-cost, non-toxic, and efficient solar selective absorbers. In particular, association of reduced graphene oxide (rGO) and nickel oxide (NiO) could facilitate highly ascertained optical properties, environment friendliness, and low-cost. Present study focuses on preparing a novel, high performance, and low-cost rGO-NiO solar selective absorber thin films. Thin films comprised of reduced graphene oxide modified nickel oxide nanocomposites (rGO-NiO NCs) were prepared through solvothermal route and coated on aluminum (Al) substrates by dip-coating technique. The rGO-NiO NCs examined using X-ray diffractometer revealed formation of face centered cubic crystallite structure. The scanning electron microscope images disclosed spherical morphology of NiO decorated on the rGO sheets. The spectra derived from energy-dispersive X-ray spectroscopy ascertained absence of peaks corresponding to impurities. The Raman investigation exhibited high intensity ratio (0.97) of the rGO-NiO NCs that described higher disorder and binding sites. The optical property analysis of the rGO-NiO NC (0.2 wt% rGO) thin film performed in UV–vis-NIR reflectance spectroscopy showed high absorptance (α = 88.03 %) and low thermal emittance (ε = 4.5 %), which eventually delivered high solar selectivity (ξ) of 19.56. These findings suggest that the prepared 0.2 % rGO-NiO NC thin film can be utilized as an appropriate selective absorber for solar to thermal energy conversion.

Nano-SnO2/polyaniline composite films for surface plasmon resonance

Synthesized nanocomposites of protonated polyaniline with camphor sulfonic acid (PANI-CSA) doped with tin oxide nanoparticles (SnO2 NPs) were coated as films on fused silica substrates using the dip-coating technique. The optical, electrical, chemical and thermal properties of the produced (PANI-CSA)/SnO2 were investigated. The refractive index for (PANI-CSA)/SnO2 nanocomposite films increases with increasing SnO2 NPs mole fraction. The optical bandgap energy of undoped PANI-CSA thin films is 4.34 eV, being this value decreased in a monoexponentially decay to 4.08 eV for samples up to a 0.11-mol fraction of SnO2 NPs in PANI-CSA. For a 0.20-mol fraction the bandgap has a substantial decrease (3.93 eV) due to SnO2 NPs percolations. Upon inceasing SnO2 MPs content the electrical conductivity of the (PANI-CSA)/SnO2 nanocomposite films reaches a threshold of 2.25 [S.cm−1]. A surface plasmon resonance (SPR) theoretical model consisting in a prism with Au/(PANI-CSA)/SnO2 layers shows that the SPR sensitivity for particle detection increases with increasing SnO2 NPs concentration.

Optical investigations of Cu2BaSnS4 quaternary nanostructure absorbers deposited by dip-coating technique

Optical investigations of Cu2BaSnS4 quaternary nanostructure absorbers deposited by dip-coating technique

An eco-friendly and intumescent P/N/S-containing flame retardant coating for polyamide 6 fabric

This study focused on the construction of an eco-friendly and intumescent flame retardant (FR) coating for polyamide 6 (PA6) fabric. The intumescent FR coating, consisting of phytic acid, pentaerythritol and thiourea, was deposited onto PA6 fabric through dip-coating technique. The FR performance, anti-dripping ability, thermal stability, combustion behavior and mechanical property of the coated PA6 fabrics were explored. The severe dripping of coated PA6 fabric was totally eliminated, achieving an excellent FR performance at a low P (2.2%) and S (3.4%) content. Correspondingly, the LOI increased to 28.8% versus 23.2% of pristine one, displaying good flame retardancy. The char residue analyses confirmed the intumescent FR behavior of coated PA6 fabrics. The intumescent char layer played a major role in isolating the exchange of combustibles, oxygen and heat, leading to the significant reduction in heat release performance. The results of cone calorimetry test showed that the peak heat release rate and average effective heat of combustion of coated PA6 fabric decreased by about 36.5% and 34.4%, respectively versus pristine one. Meanwhile, the sulfur-based gases captured free radicals to interrupt the continuous combustion, leading to the significantly improved flame retardancy. Furthermore, the FR coating exerted little influence on the mechanical performance of PA6 fabric.

Hydrophobic Material: Effect of Alkyl Chain Length on the Surface Roughness

The clean technologies of self-cleaning surfaces are expanding rapidly. Highly hydrophobic coatings with strong adhesion, high durability, and dirt-free surfaces have been prepared via sol-gel deposition of SiO2-TiO2-alkylsilane. The influence of the effects of the alkyl chain length of silane on surface roughness was investigated. This deposition involved a one-layer technique to produce the rough surfaces. The bimetal oxide of SiO2-TiO2 created a high level of surface roughness. As a result, the water contact angle of the coatings increased with the increasing alkyl chain length of silane (up to C=8). However, the water contact angle decreased when the C=16 of alkylsilane was applied. It was predicted that the longer alkyl chain would cause the molecules to collapse. The higher hydrophobicity was produced by SiO2-TiO2-OTMS coatings with a water contact angle of about 140.67 ± 1.23°. The effect of the dip-coating technique (one layer and layer-by-layer) on hydrophobicity was also discussed. The results showed that coatings produced by the one-layer technique had a higher contact angle than coatings made by the layer-by-layer technique. The coatings were stable under outdoor exposure and able to hinder dirt attachment to their surfaces.

Low-cost 3D-printing system for the deposition of reduced graphene oxide (rGO) thin films by dip-coating with application for electrode fabrication

A low-cost 3D-printing system is reported for the deposition of thin films by a dip-coating technique. The structure was constructed using 3D-printed pieces of polylactic acid (PLA) joined by simple snap-fit. This structure assembly and design simplifies the construction and replicability of dip-coating equipment. The components used are affordable and accessible, reducing the cost of implementation. An Arduino controls the system through a C++ program that varies the pulling and dipping speed from 0.5 to 20 mm/s. The pulling and dipping process uses a servomotor motion transformed into linear by a rack and pinion mechanism. The performance of the presented system was validated by comparison of thin-film reduced graphene oxide (rGO) deposition onto gold. The rGO thin films obtained were homogeneous and smooth, capable of being used as electrodes in biosensors.

Effects of Polystrene (PS) Molecular Weight and Metal Oxide (TiO2) Content of PS Latex/TiO2 Nanocomposites on Their Film Formation Behavior

Our aim for the research described here was to investigate the effects of the molecular weight (Mw) of the polystrene (PS) latex and the nano-metal oxide (TiO2) content of PS latex/TiO2 nanocomposites on their film formation behavior. With the steady-state fluorescence (SSF) and UV-visible (UVV) techniques, the film formation was monitored through a pyrene-based fluorescence probe. Two instruments were utilized to observe the morphological alterations of the composite films: an atomic force microscope (AFM) and a scanning electron microscope (SEM). Prior to the results experiments, the composite films were prepared in two sets consisting of the latex particles with high Mw (HM) or low Mw (LM), and a dip-coating technique was used at room temperature in order to form multiple layers in each film with TiO2. Then these samples were annealed within the range of 100–280 °C, above the glass transition temperature (T g) of PS. Throughout the annealing process, the film formation was monitored stage by stage based on the fluorescence intensity (I p) emitted from added pyrene and the transmitted light intensity (I tr) levels. All the measurements resulted in completion of film formation, independent of the Mw of the PS latexes or the TiO2 content. However, while the void closure process was not observed in the LM films, whose packaging structure was much simpler than that of the HM films, it was observed in the HM films. At the end of the process, a porous structure was obtained by extracting the PS polymer using toluene as the solvent. The surface appearance of the sample films varied according to both the different amounts of TiO2 layers in the composite films and the molecular weight of the PS latexes. For the HM films, interconnected porosity was produced at all TiO2 contents, whereas interconnected pores were not observed for more than 5 TiO2 layers contents in the LM samples. Furthermore, the spectroscopic measurements and the SEM/AFM images indicated that the film formation of the PS latexes took place primarily in the PS layers on the top and bottom film surfaces.

Influence of Al content on microstructure and optical transmittance of sol-gel dip-coated ZnO films

Aluminum-doped zinc oxide thin film (Al:ZnO) was derived by the sol-gel dip-coating technique to analyze the doping effect on the film’s crystal structure and optical transparency. The surface structure of the thin film had the particles in the nano-spherical form. Al amount changed surface roughness with the variation of the grain size. The crystal structure of ZnO was wurtzite (in XRD analysis). The surface morphology of the film was also examined with SEM images. The effect of Al doping was investigated to evaluate the necessary amount of Al on the optical properties. The films show high optical transparency (~85%) at specific Al doping amounts (0.8-1.6%).

Impact of Cu on structural, optical, dielectric properties and antibacterial activity of TiO2 thin films

In this work, Copper-doped TiO2 thin films were synthesized on glass substrates using a sol-gel dip-coating technique with varied molar concentrations of copper precursor (1,3,5,7,9 at. wt. %). Cu affected the structural, morphological, dielectric, antibacterial, and optical properties of TiO2 films. The formation of the anatase phase was confirmed by XRD. The morphology of all synthesized thin films was spherical grains with slight aggregation. The hopping process explained dielectric characteristics that obeyed the Maxwell-Wagner model and Koop's theory. These films were ideal for high-frequency devices because of their low dielectric constant. It was observed that as Cu concentration increased, the optical band gap energy reduced, which was beneficial for improving solar cell efficiency. Cu-doped TiO2 produced the best antibacterial agent. The photocatalysts with the highest photo activities were those containing 9 wt% Cu. The increased light absorption in the UV-VIS range and the lower recombination rate of the photoinduced electron hole pair of Cu-doped TiO2 thin films were responsible for the improved photocatalytic activity. Methylene blue degraded in the presence of sunshine, making it a potential material for the treatment of water.

Preparation of Special Wettability Quartz Sand Filter Media and Its Synchronous Oil/Water Mixture Separation and Dye Adsorption

To efficiently and synchronously separate oil/water mixture and adsorbed dyes, corn-cob-covered quartz sand (CCQS) filter media with underwater superoleophobic qualities and underoil extremely hydrophobic qualities were fabricated by grafting a corn cob onto the surface of quartz sand using the dip-coating technique. Due to the introduction of more hydrogen bonds on the quartz surface and the construction of a rough structure, the underwater oil contact angles and underoil water contact angles of the CCQS were 150.3~154.6° and 132.2°~154.6°, respectively. A separator for oil/water separation was devised, and the CCQS-filled separator could synchronously separate the oil/water mixture and adsorb malachite green. The separation efficiency of the oil/water mixture was over 99.93%, the removal rate of MG was 99.73%, and the adsorption capacity was 7.28 mg/g. The CCQS could keep its wettability steady under challenging environmental circumstances. Therefore, the study offered a novel concept for the successful oil/water mixture separation, while synchronously adsorbing dye.

The effects of silica-coated Y2O2S:Eu3+ red phosphor on the lighting properties of the light-emitting diode

The red phosphor Y2O2S:Eu3+ coated with silica (SiO2) nanocomposite was synthesized using the sol-gel method with dip-coating technique. The purpose of coating the poly (methyl methacrylate) (PMMA)-SiO2 composite on Y2O2S:Eu3+ phosphor’s surface is to protect the phosphor and improve its scattering ability. The three primary ingredients of coating composition include methyl methacrylate (MMA) monomer, tetraethyl orthosilicate (TEOS), and SiO2 nanoparticles. Via Mie scattering theory, the scattering of SiO2 is examined, which primarily determines the scattering of PMMA-SiO2-coated Y2O2S:Eu3+. The larger particles of SiO2 in the coating composite leads to better scattering properties. When being applied in the dual-film remote phosphor configuration of a LED, SiO2@Y2O2S:Eu3+ considerably enhances the CRI and the color quality scale (CQS). The highest CRI and CQS can be observed at approximately 85 and 74 with 23 %wt. and 26 %wt. the concentration of SiO2@Y2O2S:Eu3+, respectively. Neverthless, the illuminating beam of the package gradually declines as the concentration of SiO2@Y2O2S:Eu3+ go up, which might be ascribed to excessive scattering occurrences in the double-layer remote package.

Synthesis and characterization of Bi1−x La x FeO3 multiferroic thin films

Lanthanum modified BiFeO3 thin films were prepared via the sol-gel method and deposited through the dip-coating technique on ITO coated substrates. The structural properties were investigated at room temperature from X-ray diffraction as well as Raman spectroscopy. Results confirm the formation of the perovskite structure without secondary phases, thus corroborating the high-quality of the obtained thin films. Well-defined and nanometric scale grains have been obtained from atomic force microscopy, revealing indeed crack-free surfaces. From the technological point of view, this result is very important since residual stresses promoted by surface cracks led to additional conduction behavior, which could affect the real electric response of the sample to be used in electronic devices.

Nanoparticles based single and tandem stable solar selective absorber coatings with wide angular solar absorptance

Solar selective absorber coatings with wide angular solar absorptance aids in attaining high photo-thermal conversion efficiency for solar thermal systems. In this regard, nanoparticles-based absorber coatings were developed on stainless steel grade 304 by combining the impregnation method, solvothermal process, and dip-coating technique. Developed nanocomposite (SiO 2 nanoparticles in transition metal oxide matrix) based single layer absorber coating with nano void textured surface, exhibits solar absorptance of 0.92 and spectral emittance of 0.12. MgF 2 nanoparticles based anti-reflective layer on single-layer absorber coating improves the solar absorptance to 0.94 by destructive interference mechanism. Both nanoparticles based single and tandem absorber coatings show wide angular solar absorptance of 0.88 and 0.89, respectively, at an incidence angle of 50°. Besides, developed absorber coatings show lower thermal emissivity of 0.17 and good photo-thermal conversion efficiencies at high operating temperatures (400–500 °C). These developed absorber coatings offer excellent thermal stability at an open atmospheric condition till operating temperature, such as 400 °C for 100 h. Selective nature with wide angular solar absorptance and low heat loss behaviour of stable absorber coating show the photo-thermal conversion efficiency of 91% can improve the performance of receiver tubes in solar thermal systems. • Cost-effective and novel nanoparticles based single and tandem absorber coatings. • Nanocomposite based absorber coating exhibits wide angular solar absorptance. • Tandem layer (MgF 2 AR/nanocomposite) absorber shows solar absorptance of 0.94 • Absorber coatings shows excellent photo-thermal conversion efficiencies (>90%). • Absorber coatings are thermally stable at 400 °C for 100 h with good adhesion.